Casting apparatus



Dec. 13, 1938. E. E. GRIFFIN CASTING APPAATUS Filed De'c. 2, 1957 2 Sheets-Sheet l WYE AN m@ Dec. 13, 1938. E. E. GRIFFIN 2,140,204

' CASTING APPARATUS Filed Dec. 2, 1937 2 Sheets-Sheet 2 Patented Dec. 13, 1938 UNITED STATES PATENT OFFICE 3 Claims.

The present invention relates to an improved centrifugal casting machine particularly for the casting of small metal articles such as articles of jewelry.

Centrifugal casting machines of the type heretofore employed for such purposes'have commonly been provided with springs which were released to drive the rotors of the machines. In an attempt to provide a sufficiently high centrifugal force at the time of starting, various more or less complicated arrangements of pivoted arms have been employed. In many cases such a machine was arranged so that the metal-containing crucible may be disposed directly on the machine and then heated by a blow torch or the like.

In general, despite the complications afforded by such machines and despite the use of the flame in direct contact with portions thereof, such ma chilies often have left much to be desired in the way of providing clean cut and sharply dened castings accurately reproducing the form of the original investments which were employed in making the moulds. The present invention aiords a simple, easily operated machine capable of use by one operator with at least two moulds at the same time and provided with removable crucibles which may be conveniently heated in an auxiliary retort or electric furnace or the like and which may quickly be applied to the machine in proper relatiornto the moulds. .To permit this desirable result, the machine is provided with Crucible and mould supporting means of novel form. The moulds are arranged so that they may be conveniently supported by such means to receive the molten metal from the crucibles. One important feature of the present invention involves the construction of the moulds, the crucibles' and the supporting means therefor, so that the molten metal is eiectively introduced into the moulds. To permit these desirable results each supporting means may C'be provided with a part disposed between the mould support and the crucible support and provided `with an v opening which registers with a reentrant portion of the mould. The cooperating crucible is provided with a surface to engage the part and with a spout insertable through the opening and into the reentrant portion of the mould. Further-l more, the Crucible is so shaped as to facilitate effective movement of the molten metal into the mould while maintaining the metal at the desired high temperature.

A further important feature of the present invention involves the arrangement of the driving means so that a very sudden torque may be imparted to the rotor of the machine, and so that the latter may have a high rate of rotary acceleration. To permit these desirable results and also to permit the firm compacting of the metal under centrifugal force, I preferably ernploy an electric driving motor which also may be provided with a fly Wheel. Accordingly driving means having a relatively high moment of inertia is provided. In accordance with this invention, a clutch is arranged between this driving means and the rotor, so that1 the vclutch may be quickly engaged to cause the sudden acceleration of the rotor. To permit this desirable result I preferably may employ a suitable cone clutch. An arrangement of this type .imparts an abrupt centrifugal impact to the molten metal, While permitting the employment of mechanism which is free from complications.

In the accompanying drawings:

Fig. 1 is a plan view of a centrifugalcasting machine constructed in accordance lwith this invention;

Fig. 2 is a sectional view of the rotor, the clutch and related parts, certain parts being shown in elevation;

Fig. 3 lis a sectional view of a portion of the rotor showing the supporting means for a mould and a Crucible with a mould and Crucible supported thereby, parts also being shown in elevation;

Figs. 4 and 5 are respectively sections on lines i-l and 5 5 of Fig. 3.

Referring to the accompanying drawings which illustrate a preferred exemplication of the present invention, it will be evident that my improved centrifugal casting machine is provided with a fixed frame including a relatively heavy base plate l supporting a driving motor 2, such as an electric motor. The latter is provided with a shaft 3 carrying a fly Wheel a portion of the shaft extending into a recessed part oi the iiy wheel, as shown in dotted lines in Fig. l, and being con- -nected by a universal joint 6 to a shaft i. 'I'he latter extends into a gear housing 8 and carries a beveled pinion 9 (shown in dotted lines in Fig. 2) which meshes with a beveled gear l0, the latter preferably being disposed in a horizontal plane and being rotatable about a vertical shaft H.- The shaft extends upwardly through the cover i3 of the gear housing 8 and is provided with a diametrical pin i4 engageable in suitably recessed portions of a bracket I5 at the center c-f the rotor i8. 'Ihe lower part of the shaft il rests on a ball 2i] mounted on the recessed end of an adjustable set screw 2l carried by a rotatable -comprises a driven member 28 slidably mounted on the splines 29 of shaft I I. An actuating fork 30 has a pivotal connection with a ring received in a grooved portion of the driven member 28.. The fork is fixed to the inner end of a pivotally mounted control lever 32 which extends through l an opening in the side of gear casing 8. The lever 32 is engageable with the upper end of a plunger 34 which is slidable in a cylinder 35 on the outer portion of the machine. This cylinder contains a compression spring 36 tending to swing the outer end of the lever to the intermediate position shown in dotted lines. Thus, when the handle is not being pressed downwardly, the driven part 28 of the clutch is out of engagement' with the driving part 23. When, however, the handle is pressed downwardly these parts are interengaged so that the gear I0 which is being driven by the motor 2 is effective in driving. the shaft II and the rotor I6.

'I'he lower wall of the gear housing is'prefs erably provided with a socket 31 affording a tapered surface to engage a corresponding surface of the driven member 28 of the clutch, thus to act as a brake when the handle 32 s pulled upwardly above its normal position.

The rotor I6 may include two oppositely disposed radial arms which are conveniently afforded by a single diametrically disposed bar 40 having upturned end portions 4 I The supporting means for the crucibles and the moulds are disposed adjoining end portions or flanges 4 I. Since the supporting means at the opposite end of the bar are similar, but one of these supporting means will be described in detail.

An upright plate 43 is disposed on the bar in inwardly spaced relation to the flange 4I and an adjustable screw 44 has a portion freely rotatable within a hollow button 45 fixed to a movable plate 41, the screw extending through an internally threaded opening in the flange 4I. 'I'he .plate 41 carries two elongate studs 49 (Fig. 1)

which extend through openings in the plate 43. Thus the plate 41 is guided vin a straight line path as the Screw 44v is screwed inwardly or outwardly. The plate 41 also carries a plurality of shorter studs 50 which may be clamped in place by nuts 5I fitting on the threaded end portions of the studs 50 (Figs. 3 and 5). Thel ends of the studs 50 are disposed in slots 54 so that the studs may be moved inwardly or outwardly on the plate and be adjusted to provide a cradle to receive a mould of desired size.

Such a mould 55 may be in the form of a metal cylinder'or shell 56 containing material such as commonly employed for dental investments which has been previously prepared to afford acasting recess or recesses. In accordance with`this invention, however, the mould is preferably provided with a reentrant portion 60 communicating through a restricted passage or passages 6I with one or more casting recesses 62. The mouldis provided with opposite planar faces to vengage the plates 41 and 43 respectively. When the mould is to be located on the machine, the screw 44 is actuated to space the plate 41 sufficiently from the plate 43 to permit the ready insertion of the mould. Since the latter preferably is cylindrical it is properly centered by resting on the studs 50. The set may be cut away'at its end remote from the plate 43 as designated by numeral 13. The inner end of the cylindrical jacket 68 is open to permit a crucible readily to be slid into place on the support.

One important feature of the present invention involves the arrangement of the parts of the crucible, of the mould and of the cooperating supporting means, and further 'important features of the invention relate to the form of the crucible itself, The crucible preferably is formed of refractory material shaped to provide a chamloer4 having an external end surface to engage the surface of the plate 43. The crucible preferably is provided with a spout 8l to project radially of the rotor I6 through the opening B4 in the plate 43 and into the reentrant part 60 of the mould. The spout may conveniently be of cylindrical form and may be provided with a bore of corresponding shape Whichcommunicates with the chamber of the crucible. The body portion of the crucible may also conveniently be of cylin- 1 drical form but the inner surface of the lower wall of the crucible is curved and inclined up- Wardly as designated by numeral so that it has a general inclination toward the bore of the spout. This arrangement not only facilitates the ow of the molten metal through the spout but it also provides a relatively thick mass of refractory material under and adjoining the surface 85, thus affording a heat-retaining means of considerable capacity in the region of the metal as it is leaving the crucible. The top of the crucible may be closed except for an opening 86 in its upper Wall at the end remote from the spout, thus the heat-retaining ability of the crucible is further enhanced. Furthermore the wall of thev crucible overhangs the chamber at each side of the opening 86 thereby providing a construction to preclude spilling of the molten metal. Itis evident that the radial direction of extent of the spout also facilitates the free iiow of the molten metal from the crucible to the recessed portion of the mould.

When a machine of this character is about to be used the motor 2 is running butJ the clutch I is disengaged. The moulds may have been formed in any desired manner to provide one or more castingrecesses 62.- In practice, if small objects such as rings are to be cast, I prefer to provide a plurality or cluster of such castin recesses which are arranged to communicate with vthe reentrant portion 60 through small channels aiaaaoa into the corresponding reentrant portions El! oi the mould. As soon as this has been accomplished, the handle 32 is actuated to cause quick engagementl of the clutch. Since the motor 2 is provided with a relatively heavy fly wheel and since the armature of the motor also has a substantial moment of inertia, the sudden engagement of the clutch is effective in causing the very rapid acceleration of the comparatively light rotor, it being evident that the clutch is-designed so that but very slight, if any slippage between the parts thereof takes place.

Since the moment of inertia of the driving parts of the machine is comparatively great and since that of the driven parts is comparatively small, the speed of the motor is but slightly changed at the instant that the clutch is engaged. As a consequence, while the crucibles 80 are being iirmly pressed against the plates 43 by centrifugal force, the molten metal is'forcibly impacted into the recessed portions of the mould, so that an unusually cleanly dened casting may be obtained.

The rotation of the motor may be continued as long as necessary to assure the eiective setting of the casting under centrifugal force, thus providing Van arrangement which is distinctly more advantageous than can be provided by the ordinary spring actuated rotor. When the metal has had time enough initiallyl to set, the .clutch may be disengaged and if desired the handle 32 may be moved to its uppermost position 'to afford a braking eiect, thus to permit the quick stopping of the rotor so that the moulds and crucibles/may be promptly removed whereupon the operation may be repeated.

It is evident that the present invention aiords a simple machine for forming small castings by the employment of centrifugal force, that the present invention permits the use of the machine fthe appended claims.

I claim: 1. Crucible for a centrifugal casting machine comprising a body of refractory material afford- I for said spout and for an opening inits upper wall at the end remote from the spout, the inner surface oi the lower wall of the chamber having a general inclination upwardly to said spout and extending a substantial fraction oi the length of the chamber.

2. Crucible for a centrifugal casting machine vide a chamber,/an outlet spout communicating with the upper part of the chamber at one end thereof, the chamber having an outer planar end surface below said spout with the spout projecting outwardly beyond said surface, the chamber providing an upwardly extending lower inner surface in the region of said spout, said inner surface extending a substantial fraction of the length of the chamber, whereby a mass of refractory material of substantial thickness is provided between said surfaces in the region `of the spout.

3. A crucible for a centrifugal casting machinecomprising a generally cylindrical body of refractory material, said body having a planar outer surface at one end, a short spout project- .ing from said end of the crucible beyond said surface, said spout being located substantially above the axis of said cylindrical body,y said crucomprising refractory material arranged to procible providing a chamber with an upwardly inclined and curved surface adjoining said spout whereby molten metal under the action of centrifugal force may readily move upwardly to4 and through said spout, said chamber being closed except for the opening provided by the spout and except for a filling opening at the upper part of the chamber at the end thereof which is remote from the spout, the crucible having overhanging walls at each side `of said lling opening, said last-named o ning extending only a minor fraction of the length of said chamber,

lsaid upwardly inclined and curved surface extending a greater fraction of the length of the chamber.

' EUGENE E. GRIFEIN. 

